docs: drop the inverted draft setup (draft=true global + 43 per-page Draft=false overrides)

[ocots]

Problem

docs/make.jl ships draft = true as the global default, and 43 content pages carry a

```@meta
Draft = false

block to opt each one back into `@example` / `@repl` execution. Net effect: everything
executes anyway — via a double negative spread across 44 files. Plus the guided tour has a
Literate `postprocess` that injects the same `Draft = false` into the generated page.

Consequences:

- A new page added without the marker is **silently not executed** — its examples never run,
  no error.
- You cannot do a quick `draft = true` pass (skip execution, check navigation / links /
  `@ref` / `@extref` / rendering) without first stripping 43 markers, because each one
  overrides the global flag.

## Fix

- `docs/make.jl`: `draft = false` as the committed default (every page executes — what a
  published build must do). Flip to `true` locally for a fast build.
- Remove the 43 `@meta Draft = false` blocks.
- Remove the guided-tour `Draft = false` Literate injection.
- To keep one page drafted while the rest execute: `Draft = true` in its `@meta` (one
  marker, opt-out, instead of 43 opt-ins).

Checked safe: the only pages without a marker are `api/ecosystem.md` (no code) and the
generated `guided-tour.md`; neither relies on being skipped. CTParser#341 is closed, so no
raw `@example` fence is transcluded un-executably any more.

## Verification

Full `julia --project=. docs/make.jl` with `draft = false`: exit 0, all `@example` / `@repl`
blocks execute (figures embedded, computed values rendered), doctests run, `@extref` 0,
`@ref` 0.